The present invention relates generally to medical devices, and more particularly to methods and apparatus for blocking or closing the lumens of blood vessels or other anatomical conduits.
In modern medical practice, it is often desirable to block or otherwise prevent flow through the lumen of a blood vessel or other anatomical conduit. Examples of medical procedures wherein it is desirable to block the lumens of blood vessels include: a) procedures intended to diminish or block the flow of blood into vascular aneurysms (e.g., cerebral aneurysms); b) procedures intended to occlude the side branches which emanate from a segment of a peripheral vein to prepare the vein segment for use as an in situ bypass conduit; c) procedures intended to treat varicose veins; d) transvascular, catheter-based procedures for bypassing obstructed, diseased or injured arteries as described in U.S. patent application Ser. Nos. 08/730,327 and 08/730,496; e) procedures intended to block or diminish blood flow to a tumor; f) procedures intended to close congenital or acquired arterio-venous malformations; and g) procedures intended to temporarily or permanently block blood flow through a vessel as an adjuvant to placement of an endovascular graft for treatment of an aneurysm or other therapeutic intervention.
Examples of embolization devices useable to block the lumens of some blood vessels have been described in the following U.S. Pat. No.: 5,382,260 to Dormandy, Jr. et al; U.S. Pat. No. 5,342,394 to Matsuno et al.; U.S. Pat. No. 5,108,407 to Geremia et al.; and U.S. Pat. No. 4,994,069 to Ritchart et al.; U.S. Pat. No. 5,382,261 to Palmaz; U.S. Pat. No. 5,486,193 to Bourne et al.; U.S. Pat. No. 5,499,995 to Teirstein; U.S. Pat. No. 5,578,074 to Mirigian; and also in Patent Cooperation Treaty International Publication No. WO96/00034 to Palermo.
The new transvascular catheter-based bypass procedures described in co-pending application Ser. Nos. 08/730,327 and 08/730,496 include certain coronary artery bypass procedures wherein a tissue-penetrating catheter is advanced, transluminally, into the coronary vasculature and is utilized to form at least one blood flow passageway (e.g., a puncture tract or interstitial tunnel) between an obstructed coronary artery and an adjacent coronary vein, at a site upstream of the arterial obstruction. Arterial blood will then flow from the obstructed coronary artery into the adjacent coronary vein. The lumen of the coronary vein is blocked or closed off immediately proximal to the first blood flow passageway such that arterial blood which enters the vein will be forced to flow through the vein in the retrograde direction. In this manner, the arterial blood from the obstructed artery may retroprofuse the myocardium through the coronary vein. Or, optionally, one or more secondary blood flow passageways (e.g., puncture tracts or interstitial tunnels) may be formed between the coronary vein into which the arterial blood has been shunted, and the obstructed artery or another coronary artery, to allow the arterial blood to re-enter the coronary arterial tree after having bypassed the arterial obstruction. In cases wherein such secondary blood flow passageways are formed between the coronary vein and one or more adjacent arteries, the lumen of the coronary vein may be blocked or closed off distal to such secondary passageways, to facilitate the re-entry of the shunted arterial blood into the coronary arterial circulation. These transvascular, catheter-based coronary artery bypass procedures present unique and heretofore unaddressed problems relating to the type(s) of blocking apparatus which may be utilized to block the lumen of the coronary vein proximal and/or distal to the arterial-venous blood flow passageways (e.g., puncture tracts or interstitial tunnels) formed during the procedure. In particular, when arterial blood is bypassed through a proximal segment of the Great Cardiac Vein, it will typically be desirable to block the lumen of the Great Cardiac Vein at or near its confluence from the coronary venous sinus. This proximal segment of the Great Cardiac Vein is of tapered or angular configuration and, as a result, the deployment of typical embolization coils of the type traditionally utilized to embolize or block the lumens of blood vessels or the defined spaces of aneurysm may be inappropriate, due to the fact that such embolization coils may become dislodged or work loose due to the gradually tapered or widening anatomy of- the proximal segment of the Great Cardiac Vein.
Accordingly, there exists a need in the art for the development of new methods and apparatus for blocking or otherwise sealing the lumens of blood vessels or other anatomical conduits, and which are usable in tapered (i.e., widening) segments of blood vessel (e.g., the proximal end of the great cardiac vein) and/or are capable of being removed following implantation and/or may be punctured or traversed following implantation.
The present invention provides methods and devices for blocking or closing the lumens of blood vessels to prevent blood flow therethrough. The devices of the present invention provide certain advantages over the prior art, such as i) possible removeability following implantation and/or ii) possible puncturability or retraverseability following implantation and/or iii) the ability to provide substantially immediate and permanent blockage of flow through a tapered or widening region of a blood vessel lumen (e.g., the proximal portion of the great cardiac vein).
The devices of the present invention generally fall into two main categoriesxe2x80x94i) implantable lumen-blocking devices, and ii) devices which are useable to weld or otherwise cause the lumenal walls of the blood vessel to constrict to a closed configuration or to constrict upon a member which has been placed within the blood vessel lumen.
The implantable lumen blocking apparatus of the present invention generally comprise i) a blood vessel engaging portion which is operative to anchor the apparatus to the surrounding wall of the blood vessel and ii) a lumen blocking portion which is operative to prevent the flow of blood in at least one direction, through the lumen of the blood vessel.
In accordance with the invention, these implantable lumen blocking apparatus are initially deployable in a radially compact configuration to facilitate their transluminal delivery through the vasculature (e.g., within a delivery catheter or other delivery tool). After reaching the desired implantation site, such lumen blocking apparatus are radially expandable to an operative configuration wherein the blood vessel engaging portion of the apparatus will engage the blood vessel wall and the lumen blocking portion of the apparatus will block the lumen of the blood vessel to prevent blood from flowing therethrough in at least one direction.
Further in accordance with the invention, the vessel-engaging portion of the apparatus may comprise a structural frame of wire or other suitable material. The lumen-blocking portion of the apparatus may comprise a membrane, sponge, fabric panel, plug, disc or other member sized to be traversely disposed within the vessel lumen to block the flow of blood.
Still further in accordance with the invention, the vessel engaging portion of the apparatus may comprise a plurality of members which emanate outwardly from a fulcrum point such that, when pressure is applied against the fulcrum point, such pressure will cause the plurality of members to become outwardly biased and thus radially expand, enlarge or exert outward pressure against the blood vessel wall, thereby deterring the apparatus from becoming dislodged or migrating from its seated position within the blood vessel.
Further in accordance with the invention, these implantable lumen-blocking apparatus may comprise radiographically visible material to permit the lumen blocking device to be visualized radiographically following implantation.
Still further in accordance with the invention, these implantable lumen-blocking apparatus may comprise resilient or shape memory material which will self-expand from its operative configuration by its own resilient force or by undergoing a phase transformation when exposed and warmed to body temperature. Alternatively, such implantable lumen blocking apparatus may comprise plastically deformable material which may be deformed from its radially compact configuration to its operative configuration by application of pressure or force. Such plastically deformable embodiments, may be initially mounted upon a delivery catheter equipped with an outward pressure exerting tool (e.g., a balloon or other mechanical means) such that, after the device has been positioned at its desired location within a blood vessel, the pressure exerting tool may be used to plastically deform the device to its radially expanded configuration wherein the engaging portion of the device will engage the vessel wall. Alternatively, some of these apparatus may be inflatable from their radially compact configuration to their operative configuration.
Still further in accordance with the invention, at least some embodiments of the implantable lumen blocking devices are removable following implantation within the lumen of a blood vessel. The means by which such removal may be effected may include a connector or other attachment, member to facilitate linkage or connection to a wire, catheter or other retraction apparatus so as to pull, retract, rescue, draw, aspirate or otherwise move the previously implanted into the lumen of the catheter or other removal vehicle to remove the apparatus from the body. Or, in embodiments wherein the vessel-engaging portion of the apparatus is formed of a shape memory alloy, the implanted apparatus may be subjectable to an in situ treatment to cause it to radially contract. Such in situ treatment may comprise the infusion of a cooled liquid (such as saline) to cause the shape memory material of the apparatus to transition from one crystalline state to another with concurrent radial contraction of the apparatus from its operative configuration to a more radially compact configuration suitable for extraction and removal.
Still further in accordance with the invention, some embodiments of the implantable lumen-blocking apparatus may incorporate a lumen-blocking portion which is retranversible (i.e. puncturable). In this manner, a needle or other puncturing element may be passed through the apparatus following its implantation to restore blood flow, or to gain access to portions of the blood vessel which are distal to the site at which the apparatus was implanted.
Still further in accordance with the invention, some embodiments of these implantable lumen-blocking apparatus may comprise a woven fabric or other tissue permeable material which will undergo cellular ingrowth or endothelialization. In these embodiments, the process of cellular ingrowth or endothelialization may be exploited to enhance the anchoring of the apparatus within the blood vessel lumen and/or to improve the long-term biocompatability of the apparatus following implantation thereof.
The invention also includes apparatus for welding the lumen of a blood vessel. In accordance with these embodiments of the invention, there are provided intraluminally insertable devices having at least one suction port and at least one energy-emitting region. Suction is applied through the suction port to cause the lumen of the blood vessel to collapse in an area adjacent the energy-emitting region of the device. Thereafter, energy is delivered from the energy-emitting region to weld, cauterize or otherwise fuse the collapsed lumenal wall of the blood vessel, thereby closing the lumen of the blood vessel at that site as an alternative to the use of emitted energy, these devices may deliver an adhesive or other chemical substance capable of adhering or chemically fusing the lumen of the blood vessel to form the desired closure of the lumen.
Further in accordance with this embodiment of the invention, there is provided an intraluminally insertable device which has a balloon formed thereon, a fluid delivery port, and an energy emitting region when the balloon is inflated, the balloon will temporarily block the vessel lumen. Thereafter, a flowable conductive medium (e.g., saline solution) may be introduced through the fluid delivery port and into the vessel lumen adjacent the location of the energy emitting region. Energy is then emitted such that the energy will be transmitted through the previously introduced conductive substance, to the wall of the blood vessel, thereby resulting in shrinkage or contraction of the vessel wall so as to result in closure of the blood vessel lumen at that site.
Still further in accordance with this aspect of the invention, there are provided intraluminal devices which deploy a core or embolic member which as a diameter smaller than the lumenal diameter of the blood vessel. These devices subsequently emit radiofrequency energy or other energy to cause the wall of the blood vessel to shrink or constrict about the previously deployed core or embolic member. Thereafter, the device may be extracted, leaving the core or embolic member firmly implanted within the shrunken or constricted region of blood vessel, thereby closing the blood vessel at that site.